Since it is impossible to measure a rotation speed of a rotor of a compressor in an inverter air conditioner directly, a method without speed measurement is applied to control the compressor. However, this method fails to achieve a closed-loop control at a low speed. Therefore, a shutdown process of the inverter air conditioner is realized generally by stopping the compressor directly or by reducing a frequency to a low frequency to directly stop the compressor, which is unable to reduce the frequency to zero.
For example, during the shutdown process of the air conditioner, after a stop signal for stopping the compressor is received, a drive signal for controlling the compressor is stopped outputting and a current of the compressor becomes to zero immediately. Under an action of a refrigerant pressure in a pipe, the compressor is stopped freely. However, due to the action of the refrigerant pressure, the compressor may be stopped in a manner of oscillation attenuation, thereby resulting in a piping vibration and affecting a piping stress.